| abstract |
Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of a mixture comprising at least two different inhibitors having structural formula ((I). In this formula, R1 and R4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl and R2 and R3 are independently selected from the group consisting of alkyl and heteroatom-substituted alkyl; and X1 and X2 (1) are independently selected from the group consisting of halogen, cyano, COOR11 (wherein R11 is alkyl or aryl) amido, -S-C6H5, -S-COCH3, -OCOC2H5, carbonyl, alkenyl (where the double bond is not conjugated with the nitroxide moiety), or alkyl of 1 to 15 carbon atoms, or (2) taken together, form a ring structure with the nitrogen. |